To obtain the accurate cause or mechanism of PCB failure or defect, basic principles and analysis processes must be followed. Otherwise, valuable failure information may be missed, resulting in the inability to continue the analysis or the possibility of obtaining incorrect conclusions. The general basic process is to first determine the failure location and mode based on the failure phenomenon through information collection, functional testing, electrical performance testing, and simple visual inspection, that is, failure localization or fault localization.

　　For simple PCBs or PCBAs, it is easy to determine the location of failure. However, for more complex BGA or MCM packaged devices or substrates, defects are not easy to observe through a microscope and cannot be determined at the moment. In this case, other means need to be used to determine.

　　Next, it is necessary to analyze the failure mechanism, using various physical and chemical methods to analyze the mechanisms that cause PCB failure or defects, such as virtual soldering, pollution, mechanical damage, wet stress, medium corrosion, fatigue damage, CAF or ion migration, stress overload, and so on.

　　Another aspect is failure cause analysis, which is based on failure mechanism and process analysis to identify the causes of failure mechanism occurrence. If necessary, experimental verification should be conducted as much as possible. Through experimental verification, accurate causes of induced failure can be found.

　　This provides a targeted basis for the next step of improvement. Finally, based on the experimental data, facts, and conclusions obtained from the analysis process, a failure analysis report should be prepared. The report should have clear facts, rigorous logical reasoning, and strong organization, and should not be imagined out of thin air.

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